Toward functionalized surfaces through surface esterification of silica

Three aspects of the esterification reaction of silica surfaces with alcohols that are relevant for the synthesis of functional materials have been studied: surface coverage, hydrolytic stability, and the introduction of functional groups. The chemisorption of alcohols on silica can be described by the Langmuir adsorption model, which allows precise control of the surface coverage. It was shown that the hydrolytic stability of the materials obtained could be significantly improved by reacting the esterified silica with hexamethyldisilazane. The use of alcohols containing mercapto groups gave silica with surface-tethered mercapto groups. These groups are available for further chemical reactions, but the hydrolytic stability of the functional material decreases in comparison to silica esterified with the corresponding nonfunctional alcohol.